A convenient and commonly used means of measuring fluid flow is by the use of ultrasonic flowmeters. This is typically accomplished by a system in which two transducers, located at angularly opposed upstream and downstream positions relative to one another are adapted to alternatively function as a transmitter and a receiver thereby causing ultrasonic signals to travel alternatively in upstream and downstream directions between the transducers. The difference in transit times between the upstream signal and the downstream signal can be used to calculate the flow rate of the fluid.
The present invention in a preferred embodiment provides a second set of transducers which are disposed in a diametrical opposed relation. These "cross path" transducers provide more information about the flow field, allowing for improvement in flow measurement accuracy and understanding of the flow field.